common use snippets in dart

Flutter_snipets.dart

//    To put bottom sheet into Stack (close on back press)
    WidgetsBinding.instance.addPostFrameCallback((_) {
      _scaffoldKey.currentState.showBottomSheet<void>(_bottomSheetBuilder);
    });

// screen sizes
const i5s = Size(320.0, 568.0);
const i8 = Size(375.0, 667.0)

// rounded button

Widget roundedButton(
  String title,
  VoidCallback onPressed, {
  double h = 50,
  double w = 200,
  double r = 5,
  double fSize = 20,
  Color color = Colors.blue,
  Color textColor = Colors.white,
}) =>
    ButtonTheme(
        height: h,
        minWidth: w,
        child: RaisedButton(
            color: fabColor,
            shape: RoundedRectangleBorder(
                borderRadius: new BorderRadius.circular(r)),
            onPressed: onPressed,
            child: Text(
              title,
              style: TextStyle(color: textColor, fontSize: fSize),
            )));

// text

String capitalize(String s) => (s != null && s.length > 1)
    ? s[0].toUpperCase() + s.substring(1)
    : s != null ? s.toUpperCase() : '';

// random color
import 'dart:math' as math;

final rnd = math.Random();

Color getRandomColor(math.Random rnd) => Color(rnd.nextInt(0xffffffff));

Color getRandomColor(math.Random rnd) => Color.fromARGB(
    255, rnd.nextInt(255), rnd.nextInt(255), rnd.nextInt(255));
    
// navigation

Navigator.push(
        context,
        MaterialPageRoute(builder: (context) => DetailedScreen(color)),
      );

Navigator.of(context).pop();

                      SchedulerBinding.instance.addPostFrameCallback((_) {
                        navigateToAuthSuccessOrErrorScreen(context,
                            AuthSuccessErrorSettings(false, widget.authType));
                      });

class CustomAnimatedRouter extends PageRouteBuilder {
  final Widget widget;

  CustomAnimatedRouter(this.widget)
      : super(
            transitionDuration: Duration(milliseconds: 500),
            pageBuilder: (BuildContext context, Animation<double> anim,
                Animation<double> secondaryAnim) {
              return widget;
            },
            transitionsBuilder: (BuildContext context, Animation<double> anim,
                Animation<double> secondaryAnim, Widget child) {
              return FadeTransition(
                opacity: Tween(begin: 0.0, end: 1.0).animate(
                    CurvedAnimation(parent: anim, curve: Curves.fastOutSlowIn)),
                child: child,
              );
            });
}

// Internec connectivity

connectivity: ^0.4.4

Future<bool> isConnectedToInternet() async {
  var connectivityResult = await (Connectivity().checkConnectivity());
  return connectivityResult == ConnectivityResult.mobile ||
      connectivityResult == ConnectivityResult.wifi;
}

// Post build delay

SchedulerBinding.instance.addPostFrameCallback(
                          (_) => model.handleItemCreated(index));